1. Field of the Invention
This invention relates to snowstorm guard fence structures and jet roofs for preventing snow damage by snowstorms to roads ans rail tracks in areas of high snowfall.
2. Conventional Technologies
Conventional means to prevent snow damage by ground snowstorm include snow fences, jet roofs and blow-up roofs. The snow fence, which is perpendicularly disposed in a place considerably spaced from one side of a road, changes the velocity of wind to form snowdrifts artificially along the fence, thereby reducing the amount of the snow reaching the road to prevent abstruction of visibility. The jet roof is disposed on a slant in a place spaced from one side of a road, and a ground snowstorm is passed through openings formed at the lower end of this roof to increase the velocity of wind, so that the blown snow swept along the surface of the road to prevent obstruction of visibility. The blow-up roof is disposed on a slant in a place spaced from one side of a cut-down road, and the direction and velocity of wind are changed along this inclined roof, so that the snow is passed over the road to prevent obstruction of visibility.
In these conventional technologies mentioned above, as the snow fence and blow-up roof are required to be disposed in a place considerably spaced from on side of a road in order to produce satisfactory results, they can not be easily construct due to difficulty in securing sites for them. The jet roofs are ineffective when snow is piled on the side of the road, and snow removal work is difficult because there is no space to discard the snow removed from the road. Moreover, the jet roof and blow-up roof have problems in which they are effective only at high wind velocity and are also difficult to use with roads having shelter structures such as medians and guard rails thereon, said shelter structures tending to create snowdrifts.
Further, the conventional jet roof is formed with jet openings at its lower end, and by utilizing the openings wind is increased in velocity. The blow snow is scattered, to prevent obstruction of visibility.
As the above-mentioned conventinal technologies are not effective when snow is piled in the jet openings at the lower end of the fences, it is required to constantly remove the piled snow therefrom, and the presence of shelter structures such as medians and guard rails on the road disturbs the flow of wind to form snowdrifts. The conventional technologies also have little effect if the direction of wind is not nearly right-angled to the fence. There also has been a problem whereby only half the road remains unobstructed at low wind velocity.